Re-Interpreting the Shift(s) in the Preston Curve: A Setback in Adult Survival in Low- and Middle-Income Countries

Ryan Hum, University of Toronto
Prabhat Jha, St Michael's Hospital and University of Toronto
Anita McGahan, University of Toronto
Yu-Ling Cheng, University of Toronto

This study examines global trends in the income required to increase survival over the last four decades. We expanded Preston’s classical log-linear relationships between economic development and life expectancy by reformulating the regression to track both the upward rise (i.e. maximum survival) and an undocumented lateral movement (i.e. critical income needed to achieve half the maximum survival) for age-group specific survival. Maximal survival have improved for all groups; however, critical income fell by over 50% for children but rose by over 100% for male and 50% for adult female. For most adult males in low- and lower-middle income countries, economic development has not resulted in gains in survival; $2.20/day is required in 2007 to attain the same mortality achieved with $1.25/day in 1970. Much of the increase in critical income can be attributed to HIV/AIDS and smoking, and can also be reduced from expanded access to technologies such as vaccinations.